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A Vec<T> can be converted to a string:
let string: String = format!("{:.?}", vec));
Can said string be converted back into a Vec<T>?
No, not for generic Ts, as the output of Debug (e.g. via #[derive(Debug)]) does not necessarily yield the right format for FromStr (if the type even implements it). Furthermore, Vec does not implement FromStr, so parse() needs at least a wrapper around the Vec.
Also, while most Debug implementation (including the derived one) show the values of their fields, they're not required to. You cannot get the lost information back at that point.
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Lots of resources online mention how Rc<RefCell> can be used to combine multiple ownership with interior mutability. This left me wondering: why is RefCell the go-to here, rather than Cell? I'm assuming this has practical limitations, but from a purely technical perspective it can be done, e.g.:
let cell = Cell::new(5);
let rc1 = Rc::new(cell);
let rc2 = rc1.clone();
rc1.set(7);
rc2.set(9);
I imagine Cell, with its more numerous restrictions, makes it less suitable for practical applications. E.g. calling any &mut self method on the contained value. This seems particularly tricky to deal with if the contained value does not implement Copy. But this is conjecture on my part. Is there a clear reasoning for this?
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self.0.iter().map(Some)
https://github.com/zcash/halo2/blob/main/halo2_proofs/src/circuit/floor_planner/v1/strategy.rs#L71
I tried to google some keywords, but didn't find any result.
There is some confusion, so let's clarify things. Some is not an enum (as you said in a comment), it's part of an enum, that is, the Option<T> type was defined as
enum Option<T> {
Some(T),
None,
}
Here, Some(T) is called a variant of this enum. However, for convenience, the compiler will produce a function with the same name, with the same signature, that simply produces that variant. That is, Some: fn(T) -> Option<T>. Similarly, the None variant produces a constant of the same name.
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If you have an instance of std::path::Path and want to write a text File to that path, what is the best way? I can call .display() to get a string and then use File I/O methods that take strings as file names, but is there a preferred way that involves something related to Path, PathBuf, etc? The .display() method is said to be lossy due to encoding issues so I would prefer a means that did not sacrifice generality.
You can use std::fs::write. The function has following signature, so it will work with Path objects too.
pub fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> Result<()>
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I'm getting this on a match block:
patterns `&Unspecified` and `&__Nonexhaustive` not covered
The code:
fn vipaddress_from_ipddress(address: &IpAddress) -> VIpAddress {
match address {
I think &Unspecified has something to do with not accounting for null case, but references in Rust cannot be null. What is &__Nonexhaustive?
Seems to be an undocumented enum variant: https://docs.rs/ethox/0.0.1-wip/src/ethox/wire/ip.rs.html#15
This possibly indicates that the developer does not expect the users of IpAddress to match; maybe there is already a function doing what you want?
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I came across one scenario where I have to identify object using Windows UI automation element.
I want to convert this object back to UITestControl, so that I can use inbuilt methods like waitforcontrol ready etc.
How Can I do this?
regards,
User232482
You can use one of the UITestControlFactory methods. Use UITestControlFactory.FromNativeElement Method (Object, String). You'll have to pass your UIAutomation element in the object parameter and the Technology name(Ex: "UIA") to the String method.More details are available in MSDN https://msdn.microsoft.com/en-us/library/microsoft.visualstudio.testtools.uitesting.uitestcontrolfactory.fromnativeelement.aspx